In a commercial process for the manufacture of adipic acid, cyclohexanol and cyclohexanone are oxidized with nitric acid in the presence of copper and vanadium catalysts. The resulting product contains adipic acid, as well as glutaric acid, and succinic acid. Conventionally, most of the adipic acid is removed from the product by crystallization, and the remaining portion of the product has in the past been treated in various processes to recover other useful products and the copper and vanadium catalyst metals. For example in U.S. Pat. No. 4,375,552 to Kuceski the stream after crystallization and removal to most of the adipic acid is treated with an alcohol to form esters which are not soluble in the aqueous phase. The esters are then removed from the stream and the catalyst metals which remain in the aqueous phase are recycled to the nitric acid oxidation step. In U.S. Pat. No. 4,316,775 to Nash the stream after crystallization and removal of most of the adipic acid is treated with methanol to form the dimethylesters of the acids, the stream is then treated with an organic solvent which extracts the acid esters, and the aqueous phase is stripped of methanol, and the remainder, containing the catalyst metals is recycled to the nitric acid oxidation of cyclohexanol and cyclohexanone step.